Effects of lanthanum on the microstructure, electrochemical behavior, and anti-corrosion properties of zinc-copper-titanium alloy in 3% sodium chloride solution

SEM analysis shows that trace amounts of La in Zn-Cu-Ti alloy can eliminate dendritic segregation and produce uniform organization. Analyses of Tafel polarization curves and EIS show that La can obviously improve the corrosion resistance of Zn-Cu-Ti alloy by two features: (i) La oxide film has strong barrier properties; (ii) with an increase in La content, the thick skeletal dendrite epsilon(primary crystal) phase disappears and the more refined and dispersed epsilon(II) phase is generated, leading to a decrease in the active cathode area. Zn-Cu-Ti-0.5La alloy has the best corrosion resistance. The corrosion of the investigated alloys is mainly selective.